Front caliper pin won't tighten

cheechy

cheechy

A2OC Donor
So as a result of my recent MOT advisory stating that I had excessively rusty discs at the front I took the opportunity to replace today given it wasn't raining for a change.

I did the driver's side without issue but upon tightening the ns the top caliper pin at the point of tightening decided it didn't want to tighten after all. So whilst the bottom pin is nice and tight the top one is in but will not actually tighten.

I'm guessing the only option here is a replacement hub carrier? I did read a piece from a couple of years back of someone using a helicoil but I don't have the expertise or materials to undertake.

If removing hub then I'm guessing that means removing the bearing and driveshaft?

Thanks
 
Yup thanks I guess so but I have been looking into a helicoil solution and it might well work out if I buy the correct kit and take my time... If not I buy another knuckle I guess?
 
You will need a new pin, you can then measure the OD and pitch to order your coil kit.
Make sure you have space to operate your drill (must run at low revs) and tap wrench.
Keep your drill bit and tap well lubricated with cutting oil. For a one off engine oil would probably suffice.
Work the tap forwards to cut then back to clear swarf. Forwards and back.
Set your coil insertion tool as instructions.
Quite satisfying when it is repaired.
Edit the thread size is a bit of an oddball. Probably to stop bag practice substituting pins with screws.
If that fails a knuckle assembly with bearing and drive flange in place is easiest option. Either from a breaker or I think I saw somebody bought a new assembly recently?
 
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Like others have said, I had this issue last week while trying to repair ( front disc & pads ) a forum members @PeteB car for MOT, I used a M9 X 1.25 mm helicoil ( Odd Size ) & all sorted,
You need to make sure you drill the hole at a correct angle then tap,
This is the second time I have come across this, failing that the stub axle need to be replaced, surprisingly both times near side front.
you have to use the original pin as it travels when braking,
If you have no luck with, I believe I have a few good pins & stub axle in my warehouse.
 
You need to drill & tap from the engine side out & again once you have put the helicoil in dont break the small tab at the end as no nut is used there leave it be.
 
Ami said:
You need to drill & tap from the engine side out & again once you have put the helicoil in dont break the small tab at the end as no nut is used there leave it be.
Click to expand...
Awesome thanks. Ended up buying an M9 X 1.25 draper kit last night which arrives tomorrow as for some reason the name gave me a bit of assurance :)

If I need to drill and cut from the inside I'm a little concerned that I won't be able to do so with the accuracy required given it needs to be ultra straight or did you remove the knuckle to repair?

Good tip on the tab incidentally!
 
No I drilled it with my battery powered drill without removing the stub axle, turned the steering to full lock a bit tight but not difficult.
 
cheechy said:
Awesome thanks. Ended up buying an M9 X 1.25 draper kit last night which arrives tomorrow as for some reason the name gave me a bit of assurance :)

If I need to drill and cut from the inside I'm a little concerned that I won't be able to do so with the accuracy required given it needs to be ultra straight or did you remove the knuckle to repair?

Good tip on the tab incidentally!
Click to expand...
Just relax and drill slowly. Through iron the drill will take the path of least resistance and be straight to the original hole. Starting the tap square is where the skill is but again in iron it will self correct.
 
Have occasionally come across cars where the thread lead in has been cross threaded at some point and it can be tricky to get a clean start.
Sometimes running the pin in and out a couple of times from the caliper side will clean up the thread.
I always use a socket mounted allen key for these and put a little pressure on the top of the caliper while turning the allen socket by hand in the opposite direction to the thread, You can feel a little click as it passes over the lead in thread. Then just turn in the correct direction for a couple of full turns before putting a ratchet anywhere near it. With a clean thread and the silicon grease on the pin it will just about go all the way in by hand.
 
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